1. Field of the Invention
This invention relates to the field of sterilization processes and in particular to indicators for sterilization cycles.
2. Description of Prior Art
In the field of cleaning, disinfection and sterilization of articles, it is desirable to determine whether a particular load of articles that is subjected to a sterilizing environment (i.e., gases such as steam, hydrogen peroxide or ethylene oxide or other environments such as a plasma) has, in fact, been exposed to an environment which should have killed the microorganisms sought to be killed. For example, U.S. Pat. No. 7,186,374 issued Mar. 6, 2007, the disclosure of which is incorporated herein by reference, discloses a method of sterilizing using vaporized hydrogen peroxide as the sterilant. It is desirable to have a simple, quick test to determine whether the sterilization environment reached the more secluded areas of the objects placed within the sterilizer.
One way of testing is to use a biological indicator as shown, for example, by U.S. Pat. No. 5,872,004 to Bolsen. Biological indicators contain a calibrated population of living organisms, e.g. bacterial spores, having a high resistance to the sterilization process under investigation. The indicator is inserted into the test chamber with the load and exposed to the sterilizing environment for the sterilizing cycle. After exposure to the sterilization cycle, the indicator is incubated in a nutrient media to encourage outgrowth of any remaining viable spores. Growth of microorganisms is an indication that the sterilization process has not been effective. U.S. Pat. Nos. 5,872,004 and 7,927,866 disclose disposable biological test packs.
Known test packs, while effective, are generally complex and costly to manufacture, requiring many parts, and can be difficult to use.